Pressure operated switch



Sept. 19, 1950 F. `W. HOTTENROTH PRESSURE OPERATED SWITCH Filed Deo. 11, 1947 lili! Patented Sept. 19, 1950 PRESSURE OPERATED SWITCH Frederick W. Hottenroth, Goshen, Ind., assignor to Penn Electric Switch Co., Goshen, Ind., a

corporation of IowaI Application December 11, 1947, Serial No. 790,985

2 Claims.

This invention relates to a switch structure wherein a mercury-to-mercury break arrangement is provided, the mercury being normally in a pair of separated pools with a barrier between them, and the circuit being made by partially displacing the mercury from the pools by raising their level due to an element entering one or both pools, the rising level causing the mercury to flow across the barrier and merge for effecting closure of the circuit and the mercury flowing by gravity oi the barrier when the displacing element is removed.

One object of the invention is to provide a relatively simple mercury switch structure wherein mercury-to-mercury break is had without complicated mechanical structure.

Another object is to provide a switch structure which may be pressure and/or temperature operated, and wherein the enclosure element for the pressure chamber seals in the mercury from atmosphere to minimize oxidation thereof upon the formation of arcs following circuit openings.

Still another object is to provide a switch structure having a pair of mercury reservoirs separated by a barrier across which the mercury can bridge when a mercury displacing element is moved into the pools of mercury.

A further object is to provide the mercury displacing element operated by a diaphragm or the like against which pressure may be built up for moving the mercury displacing element in accordance with the degree of pressure.

Still a further object is to provide a switch structure of the general character disclosed, which is comparatively simple to manufacture and assemble and inexpensive in price.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my switch whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in the accompanyingr drawing, wherein:

Figure l is a vertical sectional view of a switch structure embodying my invention and showing the switch in the open position caused by pressure build-up within its pressure chamber.

Figure 2 is a similar view showing the switch in the normal or closed position, as when there is an absence of pressure from the pressure chamber.

Figure 3 is a sectional view on the line 3-3 of Figure 1, showing details of construction.

Figure 4 is a sectional View on the line 44 of Figure 3, showing further details, and

Figure 5 is a vertical sectional view through'a modied form of my switch structure.

On the accompanying drawing I have used the reference character B to indicate in general a base member, and C a casing therefor. The base member B includes a flange I0 and a pair of mercury containing cavities I2 and I4. The cavities I2 and I4 are adapted to contain pools IB and I8 of mercury which normally rest therein, separated by a barrier 20 as shown in Figure 1 when gravity alone acts on the mercury. Terminals 22 and 24 are sealed in the base B for external circuit connections in the usual manner.

The casing C is held assembled in relation to the base B by a retainer ring 26 with a flange 28 of a diaphragm D serving as a gasket connection for sealing the space above the pools I2 and I4 in relation to the base B. The diaphragm D may be made of rubber, neoprene, or the like, having a cylindrical wall 3D and a top wall 32, and is preferably supported against collapse, due to pressure surrounding it, by a spring 3|.

Against the top wall 32 of the diaphragm D a disc 34 is positioned, having a leg 36 extending downwardly therefrom and terminating in a mercury displacing element 38. The elements 34, 36 and 38 may be part of a single member formed of insulating material, or at least the displacing element 38 should be insulating material to avoid short circuit across from the pool of mercury I6 to the pool of mercury I8.

Pressure is adapted to hold the diaphragm 32 in the position of Figure l, such pressure being introduced into the interior of the diaphragm D from a capillary tube or the like 40 (See Fig. 4) connected with a boss 42 of the base B and having '21 pIeSSllIe passageway The tube 40 may extend to a bulb for temperature operation or to any type of pressure-changing device, the pressure of which is adapted to control the switch structure which in turn may control a machine or other device that produces the temperature or pressure change. By way of example, a refrigerant or air compressor motor may be controlled by the switch structure in accordance with the pressure produced by the compressor, so that when the pressure exceeds a certain amount, the switch is opened by upward movement of the diaphragm 32 to the position 0f Figure 1.

Opposing the pressure within the diaphragm I provide a range spring 46, the tension of which may be adjusted by a screw 48. Thus the range may be set at the desired point.

Whenever the pressure goes down to a predetermined point, there will be such movement of the mercury displacing element 38 as to partially displace the pools of mercury I4 and I6, causing them to bridge the barrier 20 as shown at I5 in Figure 2, thus merging the pools of mercury. As soon as they do merge, then of course a circuit is established across the terminals 22 and 24 for energizing the motor or other device controlled by the switch structure.

Subsequently, a build-up of pressure will cause the mercury displacing element 38 to rise until the mercury iiows back into the cavities I2 and I4, and a break occurs at I5 across the barrier 20, to open the circuit with a mercury-to-mercury break. This of course eliminates the possibility of the arc damaging solid metal terminals as when there is a metal-contact-to-metal contact break, or a metal electrode-to-mercury break. At the same time, the mercury is controlled in an effective and simple manner by displacing it.

While I have shown the displacing element 38 as entering both pools of mercury, it is obvious that operation can be had by displacing the mercury from only one pool. Also, other types of actuating devices may be provided for the mercury displacing element.

By way of example in Figure 5, I show a. bellows 50 t0 the head of which the metal flange 52 of a mercury displacing element 54 may be soldered. A metal leg 56 then extends downwardly and is connected to a displacing element 54 of insulation.

In this instance the bellows is extended by a spring 58, and pressure in the tube 40 is transmitted through a boss E to the casing C'. The casing is soldered to the lower ange 82 of the bellows, so that the pressure chamber in this instance is within the casing C' but outside bellows 50. Accordingly, pressure closes the switch, whereas the switch is normally open under the action of the spring 58. Figure serves to show how the switch action can be reversed and also discloses an arrangement of diierent materials such as a metal bellows instead of a rubber diaphragm.

Some changes may be made in the construction and arrangement of the parts of my switch without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any other modified forms 0f structure or use of mechanical equivalents which may be reasonably included within their scope without sacrificing any of the advantages thereof.

I claim as my invention:

1. A switch structure comprising a. base member having a pair of pools of mercury and a baille wall between them, a mercury displacing element adapted to raise the level of at least one of said pools of mercury to cause bridging of the mercury across said baille wall to close a circuit, a flexible housing of resilient material for enclosing said pools of mercury and said mercury displacing element, said element having a head connected therewith for operation thereby, spring means opposing pressure operating within said housing to move the same in response to pressure changes, and a casing for enclosing said housing and supporting said spring means.

2. In a switch structure, a pair of pools of mercury, a mercury displacing element adapted to enter the mercury for displacing it until it bridges said pools, a exible resilient extensible housing for enclosing said pools, spring means tending to extend said housing, said spring means substantially illing said housing to support it against collapse, said housing having said mercury displacing element connected therewith, and pressure means for extending said housing to thereby cause operation of said switch structure in response to variations of the pressure.

FREDERICK W. HOTTENROTH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS France May 4. 1936 

